The former defence secretary Bob Ainsworth is suing the Daily Mail over allegations he "bungled" the rescue of a British couple kidnapped by Somali pirates.

The Coventry North East Labour MP has lodged a libel case in the high court against Associated Newspapers Ltd, the Guardian has learned.

Ainsworth said the claims – in an article about Paul and Rachel Chandler published on 12 December 2009 – were totally untrue, and were damaging to his reputation.

The story, published a month after the Chandlers were taken hostage, claimed Ainsworth had "let slip" two rescue opportunities after pirates had captured the retired Kent couple from their small yacht off the Seychelles.

The headline read: "Bob the bungler blew TWO chances to save couple held by pirates."

High court papers were lodged by Ainsworth's solicitors – libel lawyers Peter Carter-Ruck – two months ago, a week after the Chandlers were finally freed.

The Daily Mail story alleged Ainsworth had failed to act after a "series of late-night phone calls" he had with "top brass" – just as armed Royal Marine commandos were poised to storm the pirates on the high seas.

An MoD statement carried in the Daily Mail story, claimedAinsworth had in fact given the go-ahead, but that commanders were ultimately responsible for "tactical-level decisions," including about the Chandlers' safety.

Ainsworth said: "These claims are false, and the newspaper was told that. A denial was issued but they didn't publish it.

"Those phone conversations never took place. It was reputationally damaging."

Court papers for Ainsworth state an MoD denial, sent to the Daily Mail but not published, made clear he had not been involved with any of the "operational decisions".

No court hearing date has been set. It is understood lawyers representing the two sides are in discussions.